It's simple, it all boils down to how much they like what they do: self-taught programmers are passionate about what they do (that's why they started learning in the first place), while some educated programmers are not passionate (they had to learn). This difference reflects in their abilities and eagerness to learn new stuff so if you're using this as an evaluation criteria, then the percentage of self-taught programmers that are good from the total self-taught programmers will be much higher than the percentage of educated programmers from total programmers and will give the illusion that self-taught programmers are better. The reality is that it doesn't matter where someone got their knowledge from.
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